A multilayered printed circuit board so-called a multilayered built-up circuit substrate is manufactured by a semi-additive method and the like and produced by reciprocally layering conductor circuits of copper and the like and interlaminar resin insulating layers on a resin substrate reinforced with a 0.5 to 1.5 mm-thick glass cloth so-called a core. The interlaminar connection of the conductor circuits through the interlaminar resin insulating layers of the multilayered printed circuit board is performed by a via-hole.
Conventionally, the built-up multilayered printed circuit board has been manufactured by a method, for example, disclosed in JP H09-130050 A.
That is, at first, a through hole is formed in a copper-clad laminate board bearing a copper foil and successively, the substrate is plated by electroless copper plating treatment to form a plated-through hole. Next, a conductor circuit is formed by etching the surface of the substrate in a conductor pattern by employing a photolithographic technique. Next, the surface of the conductor circuit is roughened by electroless plating or etching and the like. Continuously, a resin insulating layer is formed on the conductor circuit having a roughened surface and then subjected to exposure and development treatment to form an opening part for a via-hole and after that, the interlaminar resin insulating layer is formed by UV curing and main curing.
Further, after the interlaminar resin insulating layer is roughened by roughening treatment by an acid or an oxidizing agent, a thin electroless plating film is formed and, then after a plating resist is formed on the electroless plating film, the electroless plating film is thickened by electroplating and after the plating resist is parted, etching is carried out to form a conductor circuit connected with an under-level conductor circuit through the via-hole.
After repeating these steps, finally a solder resist layer for protecting the conductor circuit is formed and the parts exposing openings for connection with electronic parts, such as an IC chip, or a mother board and the like are plated to form a pad for solder bump formation and then a solder bump is formed by printing a solder paste to the side of an electronic part such as an IC chip to manufacture a build-up multilayered printed circuit board. Further, if it is necessary, a solder bump is also formed in the mother board side.